Fix allowing empty string to be passed to resources

dsc/tests/dsc_expressions.tests.ps1

@@ -505,4 +505,22 @@ resources:
       $out.results[0].name | Should -Be 'SERVICE-api'
     }
   }
+
+  It "Expression that cannot be parsed is treated as string literal: '<expression>'" -TestCases @(
+    @{ expression = '' }
+    @{ expression = ' ' }
+  ) {
+    param($expression)
+    $yaml = @"
+`$schema: https://aka.ms/dsc/schemas/v3/bundled/config/document.json
+resources:
+- name: test
+  type: Microsoft.DSC.Debug/Echo
+  properties:
+    output: '$expression'
+"@
+    $out = dsc config get -i $yaml 2>$TestDrive/error.log | ConvertFrom-Json
+    $LASTEXITCODE | Should -Be 0 -Because (Get-Content $TestDrive/error.log -Raw | Out-String)
+    $out.results[0].result.actualState.output | Should -BeExactly $expression
+  }
 }

lib/dsc-lib/src/parser/mod.rs

@@ -51,6 +51,11 @@ impl Statement {
             return Ok(Value::String(statement.to_string()));
         }
 
+        // if statement is empty or just whitespace, return as string without parsing
+        if statement.trim().is_empty() {
+            return Ok(Value::String(statement.to_string()));
+        }
+
         let Some(tree) = &mut self.parser.parse(statement, None) else {
             return Err(DscError::Parser(t!("parser.failedToParse", statement = statement).to_string()));
         };