qmlimportscanner: When passed an invalid file/directory it should cause an error

Task-number: QTBUG-56617
Change-Id: I82eb9c07fd6350b2a63f80e62af4c0adf52656c7
Reviewed-by: J-P Nurmi <jpnurmi@qt.io>
Reviewed-by: Anton Kudryavtsev <antkudr@mail.ru>
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

tools/qmlimportscanner/main.cpp

@@ -528,7 +528,12 @@ int main(int argc, char *argv[])
             if (arg.startsWith(QLatin1Char('-')) && arg != QLatin1String("-"))
                 break;
             ++i;
-            *argReceiver += arg;
+            if (!QFile::exists(arg)) {
+                std::cerr << "No such file or directory: \"" << qPrintable(arg) << "\"\n";
+                return 1;
+            } else {
+                *argReceiver += arg;
+            }
         }
     }