Initialise config.path in case of MPQ error

Fixes #1096

d2app/app.go

@@ -241,6 +241,7 @@ func (a *App) LoadConfig() (*d2config.Configuration, error) {
 	configAsset, _ := a.asset.LoadAsset(configBaseName)
 
 	config := &d2config.Configuration{}
+	config.SetPath(d2config.DefaultConfigPath())
 
 	// create the default if not found
 	if configAsset == nil {

d2app/initialization.go

@@ -54,11 +54,11 @@ func (a *App) initialize() error {
 }
 
 const (
-	fmtErrSourceNotFound = `file not found: %s
+	fmtErrSourceNotFound = `file not found: %q
 
-Please check your config file at %s
+Please check your config file at %q
 
-Also, verify that the MPQ files exist at %s
+Also, verify that the MPQ files exist at %q
 
 Capitalization in the file name matters.
 `