PLT-6471 Properly panic when translations can't be loaded (#6414)

* PLT-6471 Properly panic when translations can't be loaded

* Print usage messages when errors occur during CLI initialization

* Reverted behaviour of FindDir and added second return value to it

* Fixed merge conflict

api4/apitestlib.go

@@ -611,7 +611,7 @@ func CheckPayLoadTooLargeStatus(t *testing.T, resp *model.Response) {
 }
 
 func readTestFile(name string) ([]byte, error) {
-	path := utils.FindDir("tests")
+	path, _ := utils.FindDir("tests")
 	file, err := os.Open(path + "/" + name)
 	if err != nil {
 		return nil, err

api4/oauth.go

@@ -323,7 +323,9 @@ func authorizeOAuthPage(c *Context, w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Security-Policy", "frame-ancestors 'self'")
 	w.Header().Set("Content-Type", "text/html")
 	w.Header().Set("Cache-Control", "no-cache, max-age=31556926, public")
-	http.ServeFile(w, r, utils.FindDir(model.CLIENT_DIR)+"root.html")
+
+	staticDir, _ := utils.FindDir(model.CLIENT_DIR)
+	http.ServeFile(w, r, staticDir+"root.html")
 }
 
 func getAccessToken(c *Context, w http.ResponseWriter, r *http.Request) {