warn if compilation result not provided

src/solidity/localDecoder.js

@@ -2,6 +2,9 @@
 
 function solidityLocals (vmtraceIndex, internalTreeCall, stack, memory) {
   var scope = internalTreeCall.findScope(vmtraceIndex)
+  if (!scope) {
+    return { 'error': 'Can\'t display locals. reason: compilation result might not have been provided' }
+  }
   var locals = {}
   for (var local in scope.locals) {
     let variable = scope.locals[local]

src/util/internalCallTree.js

@@ -20,8 +20,12 @@ class InternalCallTree {
   }
 
   buildTree (trace) {
+    if (!this.solidityProxy.loaded()) {
+      console.log('compilation result not loaded. Cannot build internal call tree')
+    } else {
       buildTree(this, 0, '', trace)
     }
+  }
 
   reset () {
     this.scopes = {}
@@ -31,7 +35,11 @@ class InternalCallTree {
   }
 
   findScope (vmtraceIndex) {
-    var scopeId = util.findLowerBoundValue(vmtraceIndex, Object.keys(this.scopeStarts))
+    var scopes = Object.keys(this.scopeStarts)
+    if (!scopes.length) {
+      return null
+    }
+    var scopeId = util.findLowerBoundValue(vmtraceIndex, scopes)
     scopeId = this.scopeStarts[scopeId]
     var scope = this.scopes[scopeId]
     var reg = /(.\d|\d)$/