Experiment with error message (#3007)

R/progress.R

@@ -76,8 +76,10 @@ Progress <- R6Class(
       min = 0, max = 1,
       style = getShinyOption("progress.style", default = "notification"))
     {
+      if (is.null(session))
+        rlang::abort("Can only use Progress$new() inside a Shiny app")
       if (is.null(session$progressStack))
-        stop("'session' is not a ShinySession object.")
+        rlang::abort("`session` is not a ShinySession object.")
 
       private$session <- session
       private$id <- createUniqueId(8)

R/react.R

@@ -65,7 +65,7 @@ Context <- R6Class(
         that have been registered with onInvalidate()."
 
       if (!identical(.pid, processId())) {
-        stop("Reactive context was created in one process and invalidated from another")
+        rlang::abort("Reactive context was created in one process and invalidated from another.")
       }
 
       if (.invalidated)
@@ -87,7 +87,7 @@ Context <- R6Class(
         immediately."
 
       if (!identical(.pid, processId())) {
-        stop("Reactive context was created in one process and accessed from another")
+        rlang::abort("Reactive context was created in one process and accessed from another.")
       }
 
       if (.invalidated)
@@ -140,9 +140,13 @@ ReactiveEnvironment <- R6Class(
         if (isTRUE(getOption('shiny.suppressMissingContextError'))) {
           return(getDummyContext())
         } else {
-          stop('Operation not allowed without an active reactive context. ',
-               '(You tried to do something that can only be done from inside a ',
-               'reactive expression or observer.)')
+          rlang::abort(c(
+            'Operation not allowed without an active reactive context.',
+            paste0(
+              'You tried to do something that can only be done from inside a ',
+              'reactive consumer.'
+            )
+          ))
         }
       }
       return(.currentContext)

R/reactives.R

@@ -105,9 +105,7 @@ ReactiveVal <- R6Class(
       invisible(TRUE)
     },
     freeze = function(session = getDefaultReactiveDomain()) {
-      if (is.null(session)) {
-        stop("Can't freeze a reactiveVal without a reactive domain")
-      }
+      checkReactiveDomain(session)
       rLog$freezeReactiveVal(private$reactId, session)
       session$onFlushed(function() {
         self$thaw(session)
@@ -238,17 +236,23 @@ freezeReactiveVal <- function(x) {
   }
 
   domain <- getDefaultReactiveDomain()
-  if (is.null(domain)) {
-    stop("freezeReactiveVal() must be called when a default reactive domain is active.")
-  }
+  checkReactiveDomain(domain)
+
   if (!inherits(x, "reactiveVal")) {
-    stop("x must be a reactiveVal object")
+    rlang::abort("`x` must be a reactiveVal.")
   }
 
   attr(x, ".impl", exact = TRUE)$freeze(domain)
   invisible()
 }
 
+checkReactiveDomain <- function(x) {
+  if (is.null(x)) {
+    rlang::abort("Can't freeze reactive values without a reactive domain.")
+  }
+}
+
+
 #' @export
 format.reactiveVal <- function(x, ...) {
   attr(x, ".impl", exact = TRUE)$format(...)
@@ -566,7 +570,7 @@ ReactiveValues <- R6Class(
 reactiveValues <- function(...) {
   args <- list(...)
   if ((length(args) > 0) && (is.null(names(args)) || any(names(args) == "")))
-    stop("All arguments passed to reactiveValues() must be named.")
+    rlang::abort("All arguments passed to reactiveValues() must be named.")
 
   values <- .createReactiveValues(ReactiveValues$new())
 
@@ -577,7 +581,7 @@ reactiveValues <- function(...) {
 
 checkName <- function(x) {
   if (!is.character(x) || length(x) != 1) {
-    stop("Must use single string to index into reactivevalues")
+    rlang::abort("Must use single string to index into reactivevalues.")
   }
 }
 
@@ -619,6 +623,14 @@ is.reactivevalues <- function(x) inherits(x, 'reactivevalues')
 #' @export
 `$.reactivevalues` <- function(x, name) {
   checkName(name)
+
+  if (!hasCurrentContext()) {
+    rlang::abort(c(
+      paste0("Can't access reactive value '", name, "' outside of reactive consumer."),
+      i = "Do you need to wrap inside reactive() or observer()?"
+    ))
+  }
+
   .subset2(x, 'impl')$get(.subset2(x, 'ns')(name))
 }
 
@@ -628,7 +640,7 @@ is.reactivevalues <- function(x) inherits(x, 'reactivevalues')
 #' @export
 `$<-.reactivevalues` <- function(x, name, value) {
   if (.subset2(x, 'readonly')) {
-    stop("Attempted to assign value to a read-only reactivevalues object")
+    rlang::abort(paste0("Can't modify read-only reactive value '", name, "'"))
   }
   checkName(name)
   .subset2(x, 'impl')$set(.subset2(x, 'ns')(name), value)
@@ -640,12 +652,12 @@ is.reactivevalues <- function(x) inherits(x, 'reactivevalues')
 
 #' @export
 `[.reactivevalues` <- function(values, name) {
-  stop("Single-bracket indexing of reactivevalues object is not allowed.")
+  rlang::abort("Can't index reactivevalues with `[`.")
 }
 
 #' @export
 `[<-.reactivevalues` <- function(values, name, value) {
-  stop("Single-bracket indexing of reactivevalues object is not allowed.")
+  rlang::abort("Can't index reactivevalues with `[`.")
 }
 
 #' @export
@@ -661,7 +673,7 @@ names.reactivevalues <- function(x) {
 
 #' @export
 `names<-.reactivevalues` <- function(x, value) {
-  stop("Can't assign names to reactivevalues object")
+  rlang::abort("Can't assign names to reactivevalues.")
 }
 
 #' @export
@@ -785,9 +797,7 @@ str.reactivevalues <- function(object, indent.str = " ", ...) {
 #' @export
 freezeReactiveValue <- function(x, name) {
   domain <- getDefaultReactiveDomain()
-  if (is.null(domain)) {
-    stop("freezeReactiveValue() must be called when a default reactive domain is active.")
-  }
+  checkReactiveDomain(domain)
 
   domain$freezeValue(x, name)
   invisible()
@@ -819,9 +829,10 @@ Observable <- R6Class(
                           domain = getDefaultReactiveDomain(),
                           ..stacktraceon = TRUE) {
       if (length(formals(func)) > 0)
-        stop("Can't make a reactive expression from a function that takes one ",
-             "or more parameters; only functions without parameters can be ",
-             "reactive.")
+        rlang::abort(c(
+          "Can't make a reactive expression from a function that takes arguments.",
+          "Only functions without parameters can become reactive expressions."
+        ))
 
       # This is to make sure that the function labels that show in the profiler
       # and in stack traces doesn't contain whitespace. See
@@ -1061,7 +1072,7 @@ execCount <- function(x) {
   else if (inherits(x, 'Observer'))
     return(x$.execCount)
   else
-    stop('Unexpected argument to execCount')
+    rlang::abort("Unexpected argument to execCount().")
 }
 
 # Internal utility functions for extracting things out of reactives.
@@ -1101,8 +1112,10 @@ Observer <- R6Class(
                           domain = getDefaultReactiveDomain(),
                           autoDestroy = TRUE, ..stacktraceon = TRUE) {
       if (length(formals(observerFunc)) > 0)
-        stop("Can't make an observer from a function that takes parameters; ",
-             "only functions without parameters can be reactive.")
+        rlang::abort(c(
+          "Can't make an observer from a function that takes arguments.",
+          "Only functions without arguments can become observers."
+        ))
       if (grepl("\\s", label, perl = TRUE)) {
         funcLabel <- "<observer>"
       } else {

R/shiny.R

@@ -1187,7 +1187,10 @@ ShinySession <- R6Class(
           private$.outputOptions[[name]] <- list()
       }
       else {
-        stop(paste("Unexpected", class(func), "output for", name))
+        rlang::abort(c(
+          paste0("Unexpected ", class(func)[[1]], " object for output$", name),
+          i = "Did you forget to use a render function?"
+        ))
       }
     },
     getOutput = function(name) {

R/utils.R

@@ -1779,7 +1779,10 @@ getSliderType <- function(min, max, value) {
     else                            "number"
   }))
   if (length(type) > 1) {
-    stop("Type mismatch for `min`, `max`, and `value`. Each must be Date, POSIXt, or number.")
+    rlang::abort(c(
+      "Type mismatch for `min`, `max`, and `value`.",
+      "All values must either be numeric, Date, or POSIXt."
+    ))
   }
   type[[1]]
 }