fix(github): remove deleted issue from issues cache

lib/modules/platform/github/index.ts

@@ -1248,6 +1248,11 @@ export async function getIssue(number: number): Promise<Issue | null> {
     return issue;
   } catch (err) /* istanbul ignore next */ {
     logger.debug({ err, number }, 'Error getting issue');
+    // istanbul ignore if
+    if (err.message === 'Response Code 410(Gone)') {
+      logger.debug(`Issue #${number} has been deleted`);
+      GithubIssueCache.deleteIssue(number);
+    }
     return null;
   }
 }

lib/modules/platform/github/issue.spec.ts

@@ -159,6 +159,32 @@ describe('modules/platform/github/issue', () => {
       });
     });
 
+    it('removes particular issue from the cache', () => {
+      cache.platform = {
+        github: {
+          issuesCache: {
+            '1': {
+              number: 1,
+              body: 'body-1',
+              state: 'open',
+              title: 'title-1',
+              lastModified: '2020-01-01T00:00:00.000Z',
+            },
+          },
+        },
+      };
+
+      GithubIssueCache.deleteIssue(1);
+
+      expect(cache).toEqual({
+        platform: {
+          github: {
+            issuesCache: {},
+          },
+        },
+      });
+    });
+
     it('reconciles cache', () => {
       cache.platform = {
         github: {

lib/modules/platform/github/issue.ts

@@ -85,6 +85,13 @@ export class GithubIssueCache {
     }
   }
 
+  static deleteIssue(number: number): void {
+    const cacheData = this.data;
+    if (cacheData) {
+      delete cacheData[number];
+    }
+  }
+
   /**
    * At the moment of repo initialization, repository cache is not available.
    * What we can do is to store issues for later reconciliation.