fix(#950): keep line-zero defects with line-specific unlint

src/main/java/org/eolang/lints/LtUnlint.java

@@ -74,7 +74,7 @@ public Collection<Defect> defects(final XML xmir) throws IOException {
         problematic.forEach(
             line -> found.forEach(
                 defect -> {
-                    if (line != 0 && defect.line() == line) {
+                    if (defect.line() == line) {
                         defects.add(defect);
                         added.set(true);
                     }

src/test/java/org/eolang/lints/LtUnlintTest.java

@@ -151,4 +151,17 @@ void catchesAllOutOfRangeDefects() throws IOException {
             Matchers.iterableWithSize(1)
         );
     }
+
+    @Test
+    void keepsLineZeroDefectWithLineSpecificUnlint() throws IOException {
+        MatcherAssert.assertThat(
+            "A line-0 defect must not be silently dropped by a line-specific unlint",
+            new LtUnlint(new LtByXsl("metas/mandatory-package")).defects(
+                new EoProgram(
+                    "org/eolang/lints/unlint-mandatory-package-line.eo"
+                ).parse()
+            ),
+            Matchers.iterableWithSize(1)
+        );
+    }
 }

src/test/resources/org/eolang/lints/unlint-mandatory-package-line.eo

@@ -0,0 +1,11 @@
+# Missing package, but it should be reported anyway.
+
++architect yegor256@gmail.com
++home https://www.eolang.org
++version 0.0.0
++spdx SPDX-FileCopyrightText: Copyright (c) 2016-2026 Objectionary.com
++spdx SPDX-License-Identifier: MIT
++unlint mandatory-package:5
+
+# Boo.
+[] > foo