fix: allow incorrect labels if placeholders are missing

src/GitVersion.Configuration.Tests/Configuration/ConfigurationExtensionsTests.cs

@@ -127,21 +127,39 @@ public void EnsureGetBranchSpecificLabelWorksWithoutEnvironmentWhenNoEnvPlacehol
     }
 
     [Test]
-    public void EnsureGetBranchSpecificLabelThrowsWhenEnvVarMissing()
+    public void EnsureGetBranchSpecificLabelReturnsLabelTemplateWhenEnvVarMissing()
     {
         var environment = new TestEnvironment();
         // Do not set MISSING_VAR
+        var expectedLabel = "pr-{env:MISSING_VAR}";
 
         var configuration = GitFlowConfigurationBuilder.New
             .WithoutBranches()
             .WithBranch(BranchName, builder => builder
-                .WithLabel("pr-{env:MISSING_VAR}")
+                .WithLabel(expectedLabel)
                 .WithRegularExpression(@"^pull[/-]"))
             .Build();
 
         var effectiveConfiguration = configuration.GetEffectiveConfiguration(ReferenceName.FromBranchName(BranchName));
-        Should.Throw<ArgumentException>(() =>
-            effectiveConfiguration.GetBranchSpecificLabel(ReferenceName.FromBranchName(BranchName), null, environment));
+        var actual = effectiveConfiguration.GetBranchSpecificLabel(ReferenceName.FromBranchName(BranchName), null, environment);
+        actual.ShouldBe(expectedLabel);
+    }
+
+    [Test]
+    public void EnsureGetBranchSpecificLabelReturnsLabelTemplateWhenPropertyMissing()
+    {
+        var expectedLabel = "{BranchName}";
+
+        var configuration = GitFlowConfigurationBuilder.New
+            .WithoutBranches()
+            .WithBranch("feature/test", builder => builder
+                .WithLabel("{BranchName}")
+                .WithRegularExpression(@"^features?[\/-]"))
+            .Build();
+
+        var effectiveConfiguration = configuration.GetEffectiveConfiguration(ReferenceName.FromBranchName(BranchName));
+        var actual = effectiveConfiguration.GetBranchSpecificLabel(ReferenceName.FromBranchName(BranchName), null, new TestEnvironment());
+        actual.ShouldBe(expectedLabel);
     }
 
     [TestCase("case-00/my-branch", "case-00-my-branch")]

src/GitVersion.Core/Extensions/ConfigurationExtensions.cs

@@ -133,8 +133,15 @@ private static bool ShouldBeIgnored(ICommit commit, IIgnoreConfiguration ignore)
             var effectiveBranchName = branchNameOverride ?? branchName;
             var labelPlaceholders = BuildLabelPlaceholders(configuration.RegularExpression, effectiveBranchName);
 
-            return label.FormatWith(labelPlaceholders, environment)
-                .RegexReplace(RegexPatterns.SanitizeLabelRegexPattern, "-");
+            try
+            {
+                return label.FormatWith(labelPlaceholders, environment)
+                    .RegexReplace(RegexPatterns.SanitizeLabelRegexPattern, "-");
+            }
+            catch (Exception e) when (e is ArgumentException or FormatException)
+            {
+                return label;
+            }
         }
 
         public TaggedSemanticVersions GetTaggedSemanticVersion()