feat(theo): When when we are likely to run into crotch trouble

packages/theo/src/front.js

@@ -12,9 +12,16 @@ export default function (part) {
     macro,
     utils,
     measurements,
-    snippets
+    snippets,
+    raise
   } = part.shorthand()
 
+  // Let's warn about some common issues
+  if ((measurements.crotchDepth - measurements.waistToHips) / measurements.hips < 0.15)
+    raise.warning(
+      'There is little vertical space to draw the cross seam. Perhaps double-check the seath depth and waist to hips measurements'
+    )
+
   // Clean up inheritedpaths & snippets
   for (let id in paths) delete paths[id]
   for (let id in snippets) delete snippets[id]
@@ -109,7 +116,7 @@ export default function (part) {
   points['-6cp'] = points[-100101].shiftOutwards(points[-6], points[-6].dist(points[-502]) / 2)
 
   // Make sure fly ends on curve
-  points.flyPretipX = utils.lineIntersectsCurve(
+  let pretipX = utils.lineIntersectsCurve(
     points[42],
     points['43beam'],
     points[-501],
@@ -119,7 +126,21 @@ export default function (part) {
   )
   // If we found mulitple points, that's not a great sign.
   // But at least we need a point instead of an array things we break
-  if (Array.isArray(points.flyPretipX)) points.flyPretipX = points.flyPretipX.pop()
+  if (Array.isArray(points.flyPretipX)) points.flyPretipX = pretipX.pop()
+  // If we found no points then we're screwed
+  if (points.flyPreTip) points.flyPretipX = pretipX
+  else {
+    raise.warning(`
+      Unable to determine fly end
+
+      We improvised to prevent the pattern from falling apart.
+      But this is almost certainly going to be a bad pattern since we're in uncharted territory.
+    `)
+    points.flyPretipX = new Path()
+      .move(points[-6])
+      .curve(points['-6cp'], points[-502], points[-501])
+      .shiftFractionAlong(0.75)
+  }
 
   points[43] = points.flyPretipX.clone()
   // Slant pocket