Fix cmd-click crash when command-mark data is unavailable

ModernTests/VT100ScreenTests.swift

@@ -679,6 +679,41 @@ class VT100ScreenTests: XCTestCase {
         })
     }
 
+    func testCommandMarkAtReturnsNilWhenLineIsOutOfBounds() {
+        let screen = self.screen(width: 10, height: 4)
+
+        screen.performBlock(joinedThreads: { _, mutableState, _ in
+            var range = VT100GridWindowedRange()
+            let negative = mutableState.commandMark(at: VT100GridCoordMake(0, -1),
+                                                    mustHaveCommand: false,
+                                                    range: &range)
+            XCTAssertNil(negative)
+
+            let tooLargeY = mutableState.numberOfLines
+            let tooLarge = mutableState.commandMark(at: VT100GridCoordMake(0, tooLargeY),
+                                                    mustHaveCommand: false,
+                                                    range: &range)
+            XCTAssertNil(tooLarge)
+        })
+    }
+
+    func testCommandMarkAtReturnsNilWhenNoMarkOnLine() {
+        let screen = self.screen(width: 10, height: 4)
+
+        appendLinesNoNewline([
+            "https://example.com",
+            "next line"
+        ], screen: screen)
+
+        screen.performBlock(joinedThreads: { _, mutableState, _ in
+            var range = VT100GridWindowedRange()
+            let mark = mutableState.commandMark(at: VT100GridCoordMake(0, 0),
+                                                mustHaveCommand: true,
+                                                range: &range)
+            XCTAssertNil(mark)
+        })
+    }
+
     private func commonNoteResizeRegressionTest(initialRange range1: VT100GridCoordRange,
                                                 intermediateRange range2: VT100GridCoordRange) {
         var screen = self.screen(width: 80, height: 25)

docs/notes-3.7.txt

@@ -648,6 +648,9 @@ Bug Fixes:
   Korean) in the AI Chat input no longer
   prematurely submits the unfinalized
   candidate text.
+- Command-clicking links in terminal output
+  no longer crashes when command-mark data
+  is unavailable.
 - Open Quickly now updates the MRU order
   when you jump to a session, so repeated
   Cmd-Shift-O Enter cycles between the two

sources/VT100Screen/VT100ScreenState.m

@@ -1251,8 +1251,21 @@ - (NSIndexSet *)foldsInRange:(VT100GridRange)gridRange {
 - (id<VT100ScreenMarkReading>)commandMarkAt:(VT100GridCoord)coord
                             mustHaveCommand:(BOOL)mustHaveCommand
                                       range:(out VT100GridWindowedRange *)rangeOut {
+    if (coord.y < 0 || coord.y >= self.numberOfLines) {
+        return nil;
+    }
+
     id<VT100ScreenMarkReading> mark = [self screenMarkOnLine:coord.y];
-    const VT100GridCoordRange range = [self coordRangeForInterval:mark.entry.interval];
+    if (!mark) {
+        return nil;
+    }
+
+    IntervalTreeEntry *entry = mark.entry;
+    if (!entry || !entry.interval) {
+        return nil;
+    }
+
+    const VT100GridCoordRange range = [self coordRangeForInterval:entry.interval];
     if (mustHaveCommand && mark.firstLineOfCommand == nil) {
         return nil;
     }