Stop file size estimation when starting the conversion

Fixes #223

Gifski/ConversionViewController.swift

@@ -118,7 +118,10 @@ final class ConversionViewController: NSViewController {
 
 		stopConversion { [weak self] in
 			// It's safe to force-unwrap as there's no scenario where it will be nil.
-			self?.push(viewController: AppDelegate.shared.previousEditViewController!)
+			let viewController = AppDelegate.shared.previousEditViewController!
+			viewController.isConverting = false
+
+			self?.push(viewController: viewController)
 		}
 	}
 

Gifski/EditVideoViewController.swift

@@ -91,8 +91,14 @@ final class EditVideoViewController: NSViewController {
 		AppDelegate.shared.previousEditViewController = self
 	}
 
+	var isConverting = false
+
 	@IBAction
 	private func convert(_ sender: Any) {
+		isConverting = true
+
+		cancelFileSizeEstimation()
+
 		let convert = ConversionViewController(conversion: conversionSettings)
 		push(viewController: convert)
 	}
@@ -476,9 +482,25 @@ final class EditVideoViewController: NSViewController {
 		return formatter.string(fromByteCount: Int64(fileSize))
 	}
 
-	private func _estimateFileSize() {
+	private func cancelFileSizeEstimation() {
 		// TODO: Deinit doesn't seem to be called.
 		self.gifski?.cancel()
+		self.gifski = nil
+
+		if estimatedSizeLabel.stringValue.contains("Calculating") {
+			setEstimatedFileSize(getNaiveEstimate().attributedString)
+		}
+	}
+
+	private func _estimateFileSize() {
+		self.gifski?.cancel()
+		self.gifski = nil
+
+		setEstimatedFileSize(getNaiveEstimate().attributedString)
+
+		guard !isConverting else {
+			return
+		}
 
 		let gifski = Gifski()
 		self.gifski = gifski

Gifski/MainWindowController.swift

@@ -29,7 +29,7 @@ final class MainWindowController: NSWindowController {
 			message: "Feedback Welcome 🙌🏻",
 			informativeText:
 				"""
-				If you have any feedback, bug report, or feature request, there's a feedback button in the “Help” menu. We respond to all submissions.
+				If you have any feedback, bug reports, or feature requests, there's a feedback button in the “Help” menu. We respond to all submissions.
 				""",
 			buttonTitles: [
 				"Get Started"