fix(ios): guard against nil markOpts and request to prevent EXC_BREAKPOINT crashes

[jtyreman-skewb]

Problem

Three force-unwrap sites in ImageMarker.swift cause EXC_BREAKPOINT (trap) crashes in production:

1 & 2 — Missing return after nil check in mark(withText:) and mark(withImage:)

Both methods check checkTextParams/checkImageParams for nil but don't return afterwards, so execution falls through into the Task block. Inside the task, markOpts is force-unwrapped:

// mark(withText:)
let images = try await loadImages(with: [(markOpts?.backgroundImage)!])  // 💥 EXC_BREAKPOINT
let scaledImage = self.markImgWithText(images[0], markOpts!)              // 💥 EXC_BREAKPOINT

// mark(withImage:)
var images = try await loadImages(with: [(markOpts?.backgroundImage)!] + waterImages!)  // 💥
let scaledImage = self.markImage(with: ..., options: markOpts!)                          // 💥

3 — Force-unwrap of request in loadImages

RCTConvert.nsurlRequest(img.src) returns an optional and can be nil for malformed URLs. It is immediately force-unwrapped:

let request = RCTConvert.nsurlRequest(img.src)
imageLoader.loadImage(with: request!, ...)  // 💥 EXC_BREAKPOINT if request is nil

These crashes are observed in production on iOS 17+ with React Native 0.73+ (both old and new architecture).

Fix

Replace all three force-unwrap patterns with guard let bindings that properly reject the JS promise with descriptive error messages instead of crashing:

• mark(withText:) / mark(withImage:): use guard let markOpts = ... else { rejecter(...); return } before the Task block
• loadImages: use guard let request = ... else { continuation.resume(throwing: error); return }
• Remove ! force-unwraps on scaledImage, waterImages, and markOpts throughout both mark methods

Testing

• Pass invalid/nil opts to markText or markImage — the JS catch block now receives a proper error instead of crashing
• Pass a malformed image URL to either mark method — handled gracefully
• Normal watermarking flow is unaffected