Duplicate entries: Return analysis, but mark as invalid with null m…

…ember

lib/backend.js

@@ -121,14 +121,16 @@ function checkConcept(concept) {
     return
   }
 
-  // allow elements two appear twice (could be error) bot not more (is probably error)
+  // allow elements to appear twice (could be error) but not more (is probably error)
   const count = {}
-  for(let i=0; i<memberList.length; i++) {
-    const id = memberList[i].notation.join(" = ")
+  for (const member of memberList.filter(Boolean)) {
+    const id = member.notation.join(" = ")
     count[id] = count[id] || 0
     if (count[id]++ >= 2) {
-      config.log(`Error: Unexpected duplicate ${id} in analysis of ${notation})`)
-      return
+      // Add `null` member to indicate an error in the analysis
+      if (!memberList.includes(null)) {
+        memberList.push(null)
+      }
     }
   }
 

lib/index.js

@@ -103,6 +103,9 @@ export async function decomposeDDC(ddc, notation) {
     }
   }
   const memberList = ((result && result.memberList) || []).map(concept => {
+    if (!concept) {
+      return concept
+    }
     if (concept.uri) {
       // Do not convert if URI already exists
       return concept

server.js

@@ -75,6 +75,9 @@ export async function createServer(
           // Check if it's necessary to swap some lines
           // TODO: Verify and test this check.
           for (let i = 1; i < memberList.length; i += 1) {
+            if (!memberList[i] || !memberList[i - 1]) {
+              continue
+            }
             if (memberList[i].notation[1] === memberList[i - 1].notation[1] && memberList[i].notation[0].length > memberList[i - 1].notation[0].length) {
               [memberList[i], memberList[i - 1]] = [memberList[i - 1], memberList[i]]
             }
@@ -84,6 +87,9 @@ export async function createServer(
             // Add broader fields to members
             const member1 = memberList[i - 1]
             const member2 = memberList[i]
+            if (!member1 || !member2) {
+              continue
+            }
             if (isMemberParentOf(member1, member2)) {
               member2.broader = [{ uri: member1.uri }]
             } else {