Fix error when whitespace occurs at end of <pre>

I had the state machine correct and made a mistake when converting it to code :/

Sources/HTMLStreamer/BlockState.swift

@@ -19,7 +19,15 @@ import Foundation
  */
 
 struct BlockStateMachine {
+    #if false
+    var blockState: BlockState = .start {
+        didSet {
+            print("\(oldValue) -> \(blockState)")
+        }
+    }
+    #else
     var blockState: BlockState = .start
+    #endif
     let blockBreak: String
     let lineBreak: String
     let listIndentForContentOutsideItem: String
@@ -70,7 +78,8 @@ extension BlockStateMachine {
             blockState = .preformattedEmptyBlock(depth: depth)
         case .afterPreStartTagWithLeadingWhitespace(let depth):
             blockState = .preformattedEmptyBlockWithLeadingWhitespace(depth: depth)
-        case .preformattedNonEmptyBlockWithTrailingWhitespace(depth: _):
+        case .preformattedNonEmptyBlockWithTrailingWhitespace(let depth):
+            blockState = .preformattedEmptyBlockWithLeadingWhitespace(depth: depth)
             temporaryBuffer.append(blockBreak)
         case .preformattedEmptyBlockWithLeadingWhitespace(depth: _):
             break

Tests/HTMLStreamerTests/AttributedStringConverterTests.swift

@@ -687,5 +687,13 @@ final class AttributedStringConverterTests: XCTestCase {
         XCTAssertEqual(convert("<p>a</p><p><br>b</p><p>c</p>"), result2)
     }
 
+    func testWhitespaceAtEndOfPre() {
+        let result = NSAttributedString(string: "a", attributes: [
+            .font: monospaceFont,
+            .paragraphStyle: NSParagraphStyle.default,
+            .foregroundColor: color,
+        ])
+        XCTAssertEqual(convert("<pre>a </pre>"), result)
+    }
     
 }