Never crash: raster and path crates without expect()/unwrap()/unreachable!()

raster: the inpainting pyramid stops at a missing level, and video inpainting falls back to a
plain patch fill if the previous frame is missing, instead of expect(). path: curve fitting of
an empty point list returns a degenerate cubic instead of indexing/unwrapping, and Merge Paths
no longer has an unreachable!() arm. Denies the panic lints in both crates.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/path/src/fit.rs

@@ -72,8 +72,7 @@ fn bern(t: f64) -> [f64; 4] {
 
 /// Solve the 2x2 normal equations for the handle lengths along the fixed tangents.
 fn generate(pts: &[Point], u: &[f64], t0: Vec2, t1: Vec2) -> CubicBez {
-    let p0 = pts[0];
-    let p3 = *pts.last().unwrap();
+    let (Some(&p0), Some(&p3)) = (pts.first(), pts.last()) else { return CubicBez::new(Point::ZERO, Point::ZERO, Point::ZERO, Point::ZERO) };
     let dir_in = -t1; // handle at the end points backwards
     let (mut c00, mut c01, mut c11, mut x0, mut x1) = (0.0, 0.0, 0.0, 0.0, 0.0);
     for (p, &t) in pts.iter().zip(u) {

crates/path/src/lib.rs

@@ -5,6 +5,8 @@
 //! pucker & bloat, zig zag, twist, wiggle, offset, merge) live in [`ops`]; curve-preserving booleans
 //! (for Merge Paths) in [`boolean`] and curve offsetting in [`offset`].
 
+#![deny(clippy::unwrap_used, clippy::expect_used, clippy::panic, clippy::unimplemented, clippy::todo, clippy::unreachable)]
+
 pub mod boolean;
 pub mod feather;
 mod fit;

crates/path/src/ops.rs

@@ -651,7 +651,8 @@ pub fn merge(paths: &[BezPath], mode: MergeMode) -> BezPath {
         MergeMode::Subtract => crate::boolean::boolean_n(&inputs, |m| m[0] && !m[1..].iter().any(|&b| b)),
         MergeMode::Intersect => crate::boolean::boolean_n(&inputs, |m| m.iter().all(|&b| b)),
         MergeMode::Exclude => crate::boolean::boolean_n(&inputs, |m| m.iter().filter(|&&b| b).count() % 2 == 1),
-        MergeMode::Merge => unreachable!(),
+        // Handled above (no boolean operation).
+        MergeMode::Merge => crate::boolean::boolean_n(&inputs, |m| m.iter().any(|&b| b)),
     }
 }