If data is missing in one of the columns, newer versions of C3 will break in an

unexpected place, which makes it hard to debug. This patch catches the error
early so as to ease debugging.

c3.js

@@ -1552,6 +1552,8 @@
             for (i = 1; i < rows.length; i++) {
                 new_row = {};
                 for (j = 0; j < rows[i].length; j++) {
+                    if (isUndefined(rows[i][j]))
+                        throw new Error("Source data is missing a component at (" + i + "," + j + ")!");
                     new_row[keys[j]] = rows[i][j];
                 }
                 new_rows.push(new_row);
@@ -1566,6 +1568,8 @@
                     if (isUndefined(new_rows[j - 1])) {
                         new_rows[j - 1] = {};
                     }
+                    if (isUndefined(columns[i][j]))
+                        throw new Error("Source data is missing a component at (" + i + "," + j + ")!");
                     new_rows[j - 1][key] = columns[i][j];
                 }
             }