🥅 Add parse error for line continuation at end of file

- it doesn't count as end of file iff there is any content after the newline after the backslash (including spaces), so catch that in an explicit case

packages/core/src/parser/util.ts

@@ -1,4 +1,5 @@
-import type { AstNode } from '../node/index.js'
+import { localize } from '@spyglassmc/locales'
+import type { AstNode, ErrorNode } from '../node/index.js'
 import { SequenceUtil, SequenceUtilDiscriminator } from '../node/index.js'
 import type { ParserContext } from '../service/index.js'
 import { ErrorReporter } from '../service/index.js'
@@ -544,6 +545,20 @@ export function concatOnTrailingBackslash<N extends Returnable>(
 			// next line's first non-whitespace character
 			const from = src.getCharRange()
 			src.nextLine()
+
+			// Minecraft raises a `Line continuation at end of file` if a backslash
+			// (+ optional whitespace to the next line) is right before the end of the file
+			if (!src.canRead()) {
+				const ans: ErrorNode = {
+					type: 'error',
+					range: Range.span(from, src),
+				}
+				ctx.err.report(
+					localize('mcfunction.parser.line-continuation-end-of-file'),
+					ans,
+				)
+			}
+
 			src.skipSpace()
 			const to = src.getCharRange(-1)
 			indexMap.push({

packages/core/test/parser/util.spec.ts

@@ -146,6 +146,9 @@ describe('concatOnTrailingBackslash()', () => {
 				{ content: 'tru\\ \n \\\n e' },
 				{ content: 'tru\\e \\ \n e' },
 				{ content: 'tru\\\n\ne' },
+				{ content: 'tru\\' },
+				{ content: 'tru\\ \n' },
+				{ content: 'tru\\ \n ' },
 			],
 		},
 	]

packages/locales/src/locales/en.json

@@ -75,6 +75,7 @@
   "mcfunction.parser.entity-selector.player-name.too-long": "Player names cannot be longer than %0% characters",
   "mcfunction.parser.eoc-unexpected": "Expected more arguments",
   "mcfunction.parser.leading-slash": "a leading slash %0%",
+  "mcfunction.parser.line-continuation-end-of-file": "A line continuation cannot be the end of the file",
   "mcfunction.parser.no-permission": "Permission level %0% is required, which is higher than %1% defined in config",
   "mcfunction.parser.objective.too-long": "Objective names cannot be longer than %0% characters",
   "mcfunction.parser.range.min>max": "The minimum value %0% is larger than the maximum value %1%",