fix: throw clear error for zero/negative pitch in quad footprints

src/fn/quad.ts

@@ -86,6 +86,21 @@ export const quadTransform = <T extends z.infer<typeof base_quad_def>>(
       `Conflicting lrpl (${v.lrpl}) and leftrightpadlength (${v.leftrightpadlength})`,
     )
   }
+  if (v.p !== undefined && v.p <= 0) {
+    throw new Error(
+      `Invalid pitch (p=${v.p}): pitch must be a positive number. Use a non-zero value like p0.5mm.`,
+    )
+  }
+  if (v.px !== undefined && v.px <= 0) {
+    throw new Error(
+      `Invalid horizontal pitch (px=${v.px}): pitch must be a positive number.`,
+    )
+  }
+  if (v.py !== undefined && v.py <= 0) {
+    throw new Error(
+      `Invalid vertical pitch (py=${v.py}): pitch must be a positive number.`,
+    )
+  }
   v.leftrightpadwidth = v.leftrightpadwidth ?? v.lrpw
   v.leftrightpadlength = v.leftrightpadlength ?? v.lrpl
 

tests/quad-zero-pitch.test.ts

@@ -0,0 +1,30 @@
+import { test, expect } from "bun:test"
+import { fp } from "../src/footprinter"
+
+test("lcc with zero pitch throws a clear error", () => {
+  expect(() => fp.string("lcc_p0mm").circuitJson()).toThrow(
+    /pitch must be a positive number/,
+  )
+})
+
+test("qfn16 with zero pitch throws a clear error", () => {
+  expect(() => fp.string("qfn16_p0mm").circuitJson()).toThrow(
+    /pitch must be a positive number/,
+  )
+})
+
+test("quad with zero px throws a clear error", () => {
+  expect(() => fp.string("quad16_w4_h4_p0.5mm_px0mm").circuitJson()).toThrow(
+    /pitch must be a positive number/,
+  )
+})
+
+test("normal pitch still works", () => {
+  const soup = fp.string("quad16_w4_l4_p0.4_pw0.25_pl0.4").circuitJson()
+  const pads = soup.filter((e) => e.type === "pcb_smtpad")
+  expect(pads.length).toBeGreaterThan(0)
+  for (const pad of pads) {
+    expect(Number.isNaN(pad.x)).toBe(false)
+    expect(Number.isNaN(pad.y)).toBe(false)
+  }
+})