Fail with exit code if migration fails

Fixes #18

migrate-db.ts

@@ -80,10 +80,12 @@ async function runMigrations(missingMigrations: Set<string>) {
     } catch (error) {
       console.log('Failed!');
       console.error(error);
+      throw error;
     }
   }
 }
 
+try {
   const missingMigrations = await getMissingMigrations();
 
   await runMigrations(missingMigrations);
@@ -91,3 +93,9 @@ await runMigrations(missingMigrations);
   if (missingMigrations.size === 0) {
     console.log('No migrations to run!');
   }
+
+  Deno.exit(0);
+} catch (error) {
+  console.error(error);
+  Deno.exit(1);
+}