1 files changed, 3 insertions, 0 deletions
diff --git a/space.js b/space.js
index 1828dda..65b5355 100644
--- a/space.js
+++ b/space.js
@@ -53,6 +53,7 @@ function Space(){
   }
 
   this.towrite = function(){ // Does no splitting or anything like that. Just returns a list of triplets for the write function
+    if (this.loc[0] === undefined) throw "Space.towrite() requires valid loc";
     let writes = [];
     for (let line = 0; line < this.data.length; line++) for (let chr = 0; chr < this.data[line].length; chr++){
       if (this.data[line][chr] == '') continue; // Internal coding for "do not write"
@@ -138,6 +139,7 @@ function Space(){
   }
 
   this.subsection = function(range){ // range is a coordinate pair
+    if (range.length !== 2 || range[0].length !== 2) throw "not subsecting a coord pair";
     // Similarly excludes this.loc
     newspace = new Space();
     for (let line=range[0][0]; line<range[1][0]; line++){
@@ -147,6 +149,7 @@ function Space(){
         newspace.data[line-range[0][0]].push(thisline[chr] || '');
       }
     }
+    newspace.loc = [range[0][0], range[0][1]];
     return newspace;
   }