Avoiding 'pc is undefined' failures

src/core/fonts.js

@@ -3507,6 +3507,11 @@ var Font = (function FontClosure() {
                 callstack.push({data: data, i: i, stackTop: stack.length - 1});
                 functionsCalled.push(funcId);
                 var pc = ttContext.functionsDefined[funcId];
+                if (!pc) {
+                  warn('TT: CALL non-existent function');
+                  ttContext.hintsValid = false;
+                  return;
+                }
                 data = pc.data;
                 i = pc.i;
               }
@@ -3527,6 +3532,11 @@ var Font = (function FontClosure() {
               lastEndf = i;
             } else {
               var pc = callstack.pop();
+              if (!pc) {
+                warn('TT: ENDF bad stack');
+                ttContext.hintsValid = false;
+                return;
+              }
               var funcId = functionsCalled.pop();
               data = pc.data;
               i = pc.i;

test/pdfs/issue3405.pdf.link

@@ -0,0 +1 @@
+https://dl.dropboxusercontent.com/s/ls9pn5hww7fer8g/pdfPrintDelFor%260%40-CN.pdf?token_hash=AAHBhbxH7bHCtUESjOikWXAh7YQfCczr3lgcn7Fbq9WEUA&disable_range=1

test/test_manifest.json

@@ -918,6 +918,14 @@
       "link": true,
       "type": "eq"
     },
+    {  "id": "issue3405",
+      "file": "pdfs/issue3405.pdf",
+      "md5": "58bd4bf790f15f849d1c932e3eda0406",
+      "rounds": 1,
+      "lastPage": 1,
+      "link": true,
+      "type": "eq"
+    },
     {  "id": "issue2006",
       "file": "pdfs/issue2006.pdf",
       "md5": "71ec73831ece9b508ad20efa6ff28642",