fix: avoid failure when inserting another credential for a user

resolves ExpressGateway#856
insertCredential will call dao's getAllCredentials() which can handle
key-auth and jwt type credentials that were affected by the bug
some extra error handling were also added

lib/services/credentials/credential.dao.js

@@ -124,7 +124,18 @@ dao.insertCredential = function (id, type, credentialObj) {
 };
 
 dao.getCredential = function (id, type) {
-  return db.hgetall(buildIdKey(type, id)).then(credential => {
+  const key = buildIdKey(type, id);
+  return db.type(key).then(type => {
+    if (type === 'hash') {
+      return db.hgetall(key)
+    } else if (type === 'set') {
+      throw Error(`Implementation error: ${key} is a set, therefore getAllCredentials() should be called instead of getCredential()`);
+    } else if (type === 'none') {
+      return null;
+    } else {
+      throw Error(`Corrupt data found at ${key}`);
+    }
+  }).then(credential => {
     if (!credential || Object.keys(credential).length === 0) return null;
     credential.isActive = credential.isActive === 'true'; // Redis has no bool type, manual conversion
     credential.type = type;

lib/services/credentials/credential.service.js

@@ -45,10 +45,24 @@ s.insertCredential = function (id, type, credentialDetails) {
     throw new Error(`Invalid credential type: ${type}`); // TODO: replace with validation error
   }
 
-  return this.getCredential(id, type) // check if credential already exists
+  return credentialDao.getAllCredentials(id) // check if credential already exists
     .then((cred) => {
-      if (cred && cred.isActive) {
-        throw new Error('Credential already exists and is active'); // TODO: replace with validation error
+      if (Array.isArray(cred)) {
+        cred.forEach((c) => {
+          if (c && typeof c.isActive !== 'boolean') {
+            throw new Error('Failed to get existing credentials'); // TODO: replace with validation error
+          }
+          if (c && c.isActive) {
+            throw new Error(`Credential ${c.keyId} already exists and is active`); // TODO: replace with validation error
+          }
+        });
+      } else {
+        if (cred && typeof cred.isActive !== 'boolean') {
+          throw new Error('Failed to get existing credentials'); // TODO: replace with validation error
+        }
+        if (cred && cred.isActive) {
+          throw new Error(`Credential ${cred.keyId} already exists and is active`); // TODO: replace with validation error
+        }
       }
       return dereferencePromise;
     })