when users shoot themselves in the foot, point them to the hospital (fixes #581)

app/src/processing/app/Base.java

@@ -2344,6 +2344,8 @@ public class Base {
         }
       }
     }
+
+    // make sure the libraries/modes/tools directories exist
     makeSketchbookSubfolders();
   }
 

app/src/processing/app/SketchName.java

@@ -31,7 +31,7 @@ public class SketchName {
    */
   static File nextFolder(File parentDir) {
     String approach = Preferences.get("sketch.name.approach");
-    if (!CLASSIC.equals(approach)) {
+    if ((approach != null) && !CLASSIC.equals(approach)) {
       WordList wl = getWordLists().get(approach);
       //File folder = wordsFolder(parentDir, approach);
       File folder = wl.wordsFolder(parentDir);

app/src/processing/app/contrib/ContributionManager.java

@@ -571,7 +571,31 @@ public class ContributionManager {
     if (!root.exists()) return;  // folder doesn't exist, nothing to update
 
     if (!root.canRead() || !root.canWrite()) {
-      throw new Exception("Please fix read/write permissions for " + root);
+      // Sometimes macOS users disallow access to the Documents folder,
+      // then wonder why there's a problem accessing the Documents folder.
+      // https://github.com/processing/processing4/issues/581
+      // TODO would like this to be in a more central location, but this is
+      //      where it's triggered most consistently, so it's here for now.
+      if (Platform.isMacOS()) {
+        // we're on the EDT here, so it's safe to show the error
+        Messages.showError("Cannot access sketchbook",
+          """
+            There is a problem with the “permissions” for the sketchbook folder.
+            Processing needs access to the Documents folder to save your work.
+            Usually this happens after you click “Don't Allow” when macOS asks
+            for access to your Documents folder. To fix:
+            
+            1. Quit Processing
+            2. Open Applications → Utilities → Terminal
+            3. Type “tccutil reset All org.processing.four” and press return
+            4. Restart Processing, and when prompted for access, click “OK”
+            
+            If that's not the problem, the forum is a good place to get help:
+            https://discourse.processing.org
+            """, null);
+      } else {
+        throw new Exception("Please fix read/write permissions for " + root);
+      }
     }
 
     File[] markedForUpdate = root.listFiles(folder ->

todo.txt

@@ -46,6 +46,12 @@ X   https://github.com/processing/processing4/issues/549
 X   put in a note about the cleaning process
 X too many temp folders prevent restart
 X   https://github.com/processing/processing4/issues/582
+X if user clicks "no" when asked to access Documents folder, will cause weird problems later
+X   "Please fix read/write" in ContributionManager.updateFlagged()
+X   but that also shouldn't prevent users from continuing
+X   https://github.com/processing/processing4/issues/581
+X   use tccutil or some api to check whether user has disallowed access
+X   https://recoursive.com/2020/03/03/reset_macos_privacy_permissions/
 
 
 _ "Show Sketch Folder" for libraries needs to treat the sketch as Untitled
@@ -58,12 +64,6 @@ _   https://github.com/processing/processing4/issues/565
 _ expanded language codes to support traditional Chinese translation
 _   https://github.com/processing/processing4/issues/600
 
-_ if user clicks "no" when asked to access Documents folder, will cause weird problems later
-_   "Please fix read/write" in ContributionManager.updateFlagged()
-_   but that also shouldn't prevent users from continuing
-_   https://github.com/processing/processing4/issues/581
-_   use tccutil or some api to check whether user has disallowed access
-
 _ preproc inserting weird number of spaces
 _   before 'public' in functions, it's an extra single space
 _   not indenting the rest of the code at all