[calamares] Reduce compile warnings in tests

- Switch debug-level to unsigned
 - Don't shadow usings; the first TR type is enough
 - The (bogus) return values were commented as // NOTREACHED,
   but still yield unreachable code warnings. Drop them
   instead, and rely on the compiler understanding [[noreturn]]
   on parser.usage().

src/calamares/testmain.cpp

@@ -80,9 +80,9 @@ handle_args( QCoreApplication& a )
     if ( parser.isSet( debugLevelOption ) )
     {
         bool ok = true;
-        int l = parser.value( debugLevelOption ).toInt( &ok );
+        unsigned int l = parser.value( debugLevelOption ).toUInt( &ok );
         unsigned int dlevel = 0;
-        if ( !ok || ( l < 0 ) )
+        if ( !ok )
             dlevel = Logger::LOGVERBOSE;
         else
             dlevel = l;
@@ -94,20 +94,20 @@ handle_args( QCoreApplication& a )
     {
         cError() << "Missing <module> path.\n";
         parser.showHelp();
-        return ModuleConfig();  // NOTREACHED
     }
-    if ( args.size() > 2 )
+    else if ( args.size() > 2 )
     {
         cError() << "More than one <module> path.\n";
         parser.showHelp();
-        return ModuleConfig();  // NOTREACHED
     }
+    else
+    {
+        QString jobSettings( parser.value( jobOption ) );
+        if ( jobSettings.isEmpty() && ( args.size() == 2 ) )
+            jobSettings = args.at(1);
 
-    QString jobSettings( parser.value( jobOption ) );
-    if ( jobSettings.isEmpty() && ( args.size() == 2 ) )
-        jobSettings = args.at(1);
-
-    return ModuleConfig{ args.first(), jobSettings, parser.value( globalOption ), parser.value( langOption ) };
+        return ModuleConfig{ args.first(), jobSettings, parser.value( globalOption ), parser.value( langOption ) };
+    }
 }
 
 
@@ -207,7 +207,7 @@ main( int argc, char* argv[] )
         return 1;
     }
 
-    using TR = Logger::DebugRow<const char*, const QString&>;
+    using TR = Logger::DebugRow<const char*, const QString>;
 
     cDebug() << "Module metadata"
         << TR( "name", m->name() )
@@ -223,7 +223,6 @@ main( int argc, char* argv[] )
         Calamares::JobResult r = p->exec();
         if ( !r )
         {
-            using TR = Logger::DebugRow<QString, QString>;
             cDebug() << count << ".. failed"
                 << TR( "summary", r.message() )
                 << TR( "details", r.details() );