Bug fix: Don't crash the type guesser when we find columns with no values in

Author: alaric-rd

lib/importer/src/dudk/backend.js

@@ -653,7 +653,7 @@ exports.SessionGuessTypes = (sid, range) => {
 
   // Initialise state, that we will refine as we go
   for (let col=0;col<columns;col++) {
-    guesses[col] = {safeTpes: undefined,
+    guesses[col] = {safeTypes: undefined,
                     maybeTypes: undefined,
                     full:true}; // This is unset if we find a blank/missing
                                 // value
@@ -725,11 +725,17 @@ exports.SessionGuessTypes = (sid, range) => {
   }
 
   // Now we must go back through the guesses and remove any safe types/formats
-  // from the maybe types/formats, so "maybe" ONLY contains options that are
+  // from the maybe types/formats, so "maybe" ONLY contains saoptions that are
   // valid for some *but not all* values; every safe type/format will be listed
   // as a maybe type/format due to the process used above.
 
+  // IN this pass, we also look for any columns that never got any guesses,
+  // because they're entirely blank - these will still have undefined for
+  // safeTypes and maybeTypes, and we should swap those for empty arrays.
+
   guesses.forEach((colGuesses) => {
+    if(!colGuesses.safeTypes) colGuesses.safeTypes = [];
+    if(!colGuesses.maybeTypes) colGuesses.maybeTypes = [];
     let maybeTypes = colGuesses.maybeTypes;
     colGuesses.safeTypes.forEach((safeFormats, typeName) => {
       if(safeFormats) {