fix(preconditions): properly check for null in ClientPermissions and UserPermissions (#262)

Co-authored-by: Tyler J Russell <[email protected]>

Author: favna

src/lib/errors/Identifiers.ts

@@ -50,6 +50,9 @@ export const enum Identifiers {
 	PreconditionGuildTextOnly = 'preconditionGuildTextOnly',
 	PreconditionNSFW = 'preconditionNsfw',
 	PreconditionClientPermissions = 'preconditionClientPermissions',
+	PreconditionClientPermissionsNoClient = 'preconditionClientPermissionsNoClient',
+	PreconditionClientPermissionsNoPermissions = 'preconditionClientPermissionsNoPermissions',
 	PreconditionUserPermissions = 'preconditionUserPermissions',
+	PreconditionUserPermissionsNoPermissions = 'preconditionUserPermissionsNoPermissions',
 	PreconditionThreadOnly = 'preconditionThreadOnly'
 }

src/preconditions/ClientPermissions.ts

@@ -21,7 +21,22 @@ export class CorePrecondition extends Precondition {
 		const required = (context.permissions as Permissions) ?? new Permissions();
 		const channel = message.channel as TextChannel | NewsChannel;
 
-		const permissions = message.guild ? channel.permissionsFor(message.client.id!)! : this.dmChannelPermissions;
+		if (!message.client.id) {
+			return this.error({
+				identifier: Identifiers.PreconditionClientPermissionsNoClient,
+				message: 'There was no client to validate the permissions for.'
+			});
+		}
+
+		const permissions = message.guild ? channel.permissionsFor(message.client.id) : this.dmChannelPermissions;
+
+		if (!permissions) {
+			return this.error({
+				identifier: Identifiers.PreconditionClientPermissionsNoPermissions,
+				message: 'I was unable to resolve my permissions in the command invocation channel.'
+			});
+		}
+
 		const missing = permissions.missing(required);
 		return missing.length === 0
 			? this.ok()

src/preconditions/UserPermissions.ts

@@ -23,7 +23,15 @@ export class CorePrecondition extends Precondition {
 		const required = (context.permissions as Permissions) ?? new Permissions();
 		const channel = message.channel as TextChannel | NewsChannel;
 
-		const permissions = message.guild ? channel.permissionsFor(message.author)! : this.dmChannelPermissions;
+		const permissions = message.guild ? channel.permissionsFor(message.author) : this.dmChannelPermissions;
+
+		if (!permissions) {
+			return this.error({
+				identifier: Identifiers.PreconditionClientPermissionsNoPermissions,
+				message: "I was unable to resolve the end-user's permissions in the command invocation channel."
+			});
+		}
+
 		const missing = permissions.missing(required);
 		return missing.length === 0
 			? this.ok()