Fix ungraceful error on non-unique OAuthClient title

app/blueprints/oauth/__init__.py

@@ -194,13 +194,18 @@ def create_edit_client(username, id_=None):
 
 	if form.validate_on_submit():
 		if is_new:
+			if OAuthClient.query.filter(OAuthClient.title.ilike(form.title.data.strip())).count() > 0:
+				flash(gettext("An OAuth client with that title already exists. Please choose a new title."), "danger")
+				return render_template("oauth/create_edit.html", user=user, form=form, client=client)
+
 			client = OAuthClient()
 			db.session.add(client)
 			client.owner = user
 			client.id = random_string(24)
 			client.secret = random_string(32)
 			client.approved = current_user.rank.at_least(UserRank.EDITOR)
 
+
 		form.populate_obj(client)
 
 		verb = "Created" if is_new else "Edited"

app/templates/oauth/create_edit.html

@@ -64,8 +64,8 @@ <h3 class="mt-0">{{ _("Application isn't approved yet") }}</h3>
 	<form method="POST" action="" enctype="multipart/form-data">
 		{{ form.hidden_tag() }}
 
-		{{ render_field(form.title) }}
-		{{ render_field(form.description, hint=_("Shown to users when you request access to their account")) }}
+		{{ render_field(form.title, hint=_("Titles must be globally unique. For example, what's the name of your application?")) }}
+		{{ render_field(form.description, hint=_("Shown to users when you request access to their account. For example, what does your application do?")) }}
 		{{ render_field(form.redirect_url) }}
 		{{ render_field(form.app_type, hint=_("Where will you store your client_secret?")) }}