Why is my JUnit class not compiling? And what can I do to make it work properly?

Here is the class I am testing:

public class Crate implements Cargo
{
    private String identifier;
    
    private double weight;

    public Crate(String idIn, double wgtIn) throws InvalidArgumentException
    {
        setIdentifier(idIn);
        setWeight(wgtIn);
    }
    
    @Override
    public String getIdentifier()
    {
        return identifier;
    }

    private void setIdentifier(String idIn) throws InvalidArgumentException
    {
        if (idIn == null || idIn.isEmpty() || idIn.length() > 20)
            throw new InvalidArgumentException("Invalid identifier passed to Crate.setIdentifier: " + idIn);
        identifier = idIn;
    }

    @Override
    public double getWeight()
    {
        return weight;
    }
    
    private void setWeight(double weightIn) throws InvalidArgumentException
    {
        if (weightIn <= 0.0)
            throw new InvalidArgumentException("Invalid weight passed to Crate.setWeight: " + weightIn);
        weight = weightIn;
    }
}

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And here is the test class for the Crate class that I wrote:

public class CrateTest {
    
    public CrateTest() {
    }

    @BeforeClass
    public static void setUpClass() throws Exception {
    }

    @AfterClass
    public static void tearDownClass() throws Exception {
    }
    
    @Before
    public void setUp() {
    }
    
    @After
    public void tearDown() {
    }

    /**
     * Test of getIdentifier method, of class Crate.
     */
    @Test
    public void testGetIdentifier() {
        Crate ct;
        
        // Positive test
        try {
            ct = new Crate("id", 3.0); 
            assertEquals("errortxt", "id", ct.getIdentifier());
            assertEquals("errortxt", 3.0, ct.getWeight(), 0.00001);
        } 
        catch (Exception e) {
            fail("Legitimate values were rejected when sent to constructor" + e.getMessage());
        }
        
        // Negative test for null String
        try {
            ct = new Crate(null, 3.0);            
            fail("errortxt");
        } 
        catch (InvalidArgumentException e) {
            assertEquals("errortxt", "Invalid identifier passed to Crate.setIdentifier: " + null, e.getMessage());
            assertEquals("errortxtONE", 0.0, ct.getWeight(), 0.00001);
        }
        
        // Negative test for empty String
        try {
            ct = new Crate("", 3.0);            
            fail("errortxt");
        } 
        catch (InvalidArgumentException e) {
            assertEquals("errortxt", "Invalid identifier passed to Crate.setIdentifier: " + "", e.getMessage());
            assertEquals("errortxtTWO", 0.0, ct.getWeight(), 0.00001);
        }
        
    }

    /**
     * Test of getWeight method, of class Crate.
     */
    @Test
    public void testGetWeight() {
    }
}

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When I attempt to compile my test the compiler complains that "variable ct may not have been initialized" on the line with "assertEquals("errortxtONE", 0.0, ct.getWeight(), 0.00001);" yet, the line with "assertEquals("errortxtTWO", 0.0, ct.getWeight(), 0.00001);" doesn't come back with an error message.

The compiler outputs the following:

Testsuite: shipexample.implementors.CrateTest
Tests run: 2, Failures: 0, Errors: 1, Time elapsed: 0.053 sec

Testcase: testGetIdentifier(shipexample.implementors.CrateTest):	Caused an ERROR
Uncompilable source code - variable ct might not have been initialized
java.lang.RuntimeException: Uncompilable source code - variable ct might not have been initialized
	at shipexample.implementors.CrateTest.testGetIdentifier(CrateTest.java:64)


Test shipexample.implementors.CrateTest FAILED
test:
Deleting: Omitted\TEST-shipexample.implementors.CrateTest.xml
BUILD SUCCESSFUL (total time: 3 seconds)

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What am I doing wrong? Why can't I use "ct.getWeight()"? And what do I need to do to my code to make this work properly? I need to somehow check to make sure the state of the Crate class "weight" data member didn't change on lines  "assertEquals("errortxtONE", 0.0, ct.getWeight(), 0.00001);"and "assertEquals("errortxtTWO", 0.0, ct.getWeight(), 0.00001);"