screenshots: add better diagnostics for failing CI

Output current UI file being processed, in case any random exception
pops up.

Change-Id: If6937f70718cc801494f424f7e09e9cb8c8758f0
(cherry picked from commit fb5d849cdeebe5299da399efc9d0ca36b6fc192b)
Reviewed-on: https://gerrit.libreoffice.org/60964
Tested-by: Jenkins
Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>

test/source/screenshot_test.cxx

@@ -247,26 +247,35 @@ void ScreenshotTest::processDialogBatchFile(const OUString& rFile)
 
     while (aStream.ReadLine(aNextUIFile))
     {
-        if (!aNextUIFile.isEmpty() && !aNextUIFile.startsWith(aComment))
+        try
         {
-            // first check if it's a known dialog
-            ScopedVclPtr<VclAbstractDialog> pDlg(createDialogByName(aNextUIFile));
-
-            if (pDlg)
-            {
-                // known dialog, dump screenshot to path
-                dumpDialogToPath(*pDlg);
-            }
-            else
+            if (!aNextUIFile.isEmpty() && !aNextUIFile.startsWith(aComment))
             {
-                // unknown dialog, try fallback to generic created
-                // VclBuilder-generated instance. Keep in mind that Dialogs
-                // using this mechanism will probably not be layouted well
-                // since the setup/initialization part is missing. Thus,
-                // only use for fallback when only the UI file is available.
-                dumpDialogToPath(aNextUIFile);
+                // first check if it's a known dialog
+                ScopedVclPtr<VclAbstractDialog> pDlg(createDialogByName(aNextUIFile));
+
+                if (pDlg)
+                {
+                    // known dialog, dump screenshot to path
+                    dumpDialogToPath(*pDlg);
+                }
+                else
+                {
+                    // unknown dialog, try fallback to generic created
+                    // VclBuilder-generated instance. Keep in mind that Dialogs
+                    // using this mechanism will probably not be layouted well
+                    // since the setup/initialization part is missing. Thus,
+                    // only use for fallback when only the UI file is available.
+                    dumpDialogToPath(aNextUIFile);
+                }
             }
         }
+        catch(...)
+        {
+            OString aMsg("Exception while processing ");
+            aMsg += aNextUIFile;
+            CPPUNIT_ASSERT_MESSAGE(aMsg.getStr(), false);
+        }
     }
 }