Values of @graph are allways in an array.

Author: gkellogg

lib/compact.js

@@ -368,7 +368,10 @@ api.compact = ({
               nestResult, itemActiveProperty, compactedItem,
               {propertyIsArray: (!options.compactArrays || container.includes('@set'))});
           } else {
-            // wrap using @graph alias
+            // wrap using @graph alias, value is always an array
+            if(!_isArray(compactedItem)) {
+              compactedItem = [compactedItem]
+            }
             compactedItem = {
               [api.compactIri({activeCtx, iri: '@graph', relativeTo: {vocab: true}})]: compactedItem
             };
@@ -844,11 +847,12 @@ api.removePreserve = (ctx, input, options) => {
     }
 
     // recurse through properties
+    const graphAlias = api.compactIri({activeCtx: ctx, iri: '@graph', relativeTo: {vocab: true}});
     for(const prop in input) {
       let result = api.removePreserve(ctx, input[prop], options);
       const container = _getContextValue(ctx, prop, '@container') || [];
       if(options.compactArrays && _isArray(result) && result.length === 1 &&
-        container.length === 0) {
+        container.length === 0 && prop !== graphAlias) {
         result = result[0];
       }
       input[prop] = result;