Right click w/ multiple lines pasted as a one line

This problem only happened in ValidateAndAcceptLine
It also only happened if validation failed for any reason.

The fix is to insert a newline even if validation failed if we still have pending input.
If there is no pending input, we don't want to insert the newline, as this is the common
case and people will not want to delete the blank line from the inserted newline.

Author: lzybkr

PSReadLine/BasicEditing.cs

@@ -238,6 +238,7 @@ private bool AcceptLineImpl(bool validate)
             _emphasisStart = -1;
             _emphasisLength = 0;
 
+            var insertionPoint = _current;
             // Make sure cursor is at the end before writing the line
             _current = _buffer.Length;
 
@@ -254,6 +255,17 @@ private bool AcceptLineImpl(bool validate)
                 var errorMessage = Validate(_ast);
                 if (!string.IsNullOrWhiteSpace(errorMessage))
                 {
+                    // If there are more keys, assume the user pasted with a right click and
+                    // we should insert a newline even though validation failed.
+                    if (_queuedKeys.Count > 0)
+                    {
+                        // Validation may have moved the cursor.  Because there are queued
+                        // keys, we need to move the cursor back to the correct place, and
+                        // ignore where validation put the cursor because the queued keys
+                        // will be inserted in the wrong place.
+                        SetCursorPosition(insertionPoint);
+                        Insert('\n');
+                    }
                     _statusLinePrompt = "";
                     _statusBuffer.Append(errorMessage);
                     _statusIsErrorMessage = true;