fix: prevent sending an invite email if not enabled (#176)

this updates the invite email sending function to prevent sending
an invite email if the environment flag is not set.  this matches
the behavior with the frontend and prevents malicious actors from
bypassing the logic

fixes #174

Author: imnotjames

src/server/mailer.ts

@@ -52,6 +52,10 @@ export async function sendSignUpEmail(email: string, token: string, url: string)
 }
 
 export async function sendInviteEmail(email: string, name: string) {
+  if (!env.ENABLE_SENDING_INVITES) {
+    throw new Error("Sending invites is not enabled")
+  }
+
   const { host } = new URL(env.NEXTAUTH_URL);
 
   if (env.NODE_ENV === 'development') {