Fix NULL pointer dereference in SCCB accessor functions

get_handle_from_address() returns NULL when the given slave address
isn't registered in devices[] (e.g. after SCCB_Deinit(), or a
concurrent deinit racing an in-flight transaction), logging
"Device with address %02x not found" as a designed graceful-failure
path. All 6 accessor functions (SCCB_Read, SCCB_Write, SCCB_Read16,
SCCB_Write16, SCCB_Read_Addr16_Val16, SCCB_Write_Addr16_Val16)
dereferenced that return value unconditionally, turning the intended
error path into a NULL pointer dereference / crash.

Add a NULL check before each dereference, returning the same failure
value each function already uses for I2C errors (0 for reads, -1 for
writes), consistent with this file's existing error-handling
convention.

Author: 94xhn

driver/sccb-ng.c

@@ -225,7 +225,12 @@ int SCCB_Probe(uint8_t slv_addr)
 
 uint8_t SCCB_Read(uint8_t slv_addr, uint8_t reg)
 {
-    i2c_master_dev_handle_t dev_handle = *(get_handle_from_address(slv_addr));
+    i2c_master_dev_handle_t *dev_handle_ptr = get_handle_from_address(slv_addr);
+    if (dev_handle_ptr == NULL)
+    {
+        return 0;
+    }
+    i2c_master_dev_handle_t dev_handle = *dev_handle_ptr;
 
     uint8_t tx_buffer[1] = { reg };
     uint8_t rx_buffer[1] = { 0 };
@@ -267,7 +272,12 @@ uint8_t SCCB_Read(uint8_t slv_addr, uint8_t reg)
 
 int SCCB_Write(uint8_t slv_addr, uint8_t reg, uint8_t data)
 {
-    i2c_master_dev_handle_t dev_handle = *(get_handle_from_address(slv_addr));
+    i2c_master_dev_handle_t *dev_handle_ptr = get_handle_from_address(slv_addr);
+    if (dev_handle_ptr == NULL)
+    {
+        return -1;
+    }
+    i2c_master_dev_handle_t dev_handle = *dev_handle_ptr;
 
     uint8_t tx_buffer[2];
     tx_buffer[0] = reg;
@@ -285,7 +295,12 @@ int SCCB_Write(uint8_t slv_addr, uint8_t reg, uint8_t data)
 
 uint8_t SCCB_Read16(uint8_t slv_addr, uint16_t reg)
 {
-    i2c_master_dev_handle_t dev_handle = *(get_handle_from_address(slv_addr));
+    i2c_master_dev_handle_t *dev_handle_ptr = get_handle_from_address(slv_addr);
+    if (dev_handle_ptr == NULL)
+    {
+        return 0;
+    }
+    i2c_master_dev_handle_t dev_handle = *dev_handle_ptr;
 
     uint8_t rx_buffer[1];
 
@@ -304,7 +319,12 @@ uint8_t SCCB_Read16(uint8_t slv_addr, uint16_t reg)
 
 int SCCB_Write16(uint8_t slv_addr, uint16_t reg, uint8_t data)
 {
-    i2c_master_dev_handle_t dev_handle = *(get_handle_from_address(slv_addr));
+    i2c_master_dev_handle_t *dev_handle_ptr = get_handle_from_address(slv_addr);
+    if (dev_handle_ptr == NULL)
+    {
+        return -1;
+    }
+    i2c_master_dev_handle_t dev_handle = *dev_handle_ptr;
 
     uint8_t tx_buffer[3];
     tx_buffer[0] = reg >> 8;
@@ -322,7 +342,12 @@ int SCCB_Write16(uint8_t slv_addr, uint16_t reg, uint8_t data)
 
 uint16_t SCCB_Read_Addr16_Val16(uint8_t slv_addr, uint16_t reg)
 {
-    i2c_master_dev_handle_t dev_handle = *(get_handle_from_address(slv_addr));
+    i2c_master_dev_handle_t *dev_handle_ptr = get_handle_from_address(slv_addr);
+    if (dev_handle_ptr == NULL)
+    {
+        return 0;
+    }
+    i2c_master_dev_handle_t dev_handle = *dev_handle_ptr;
 
     uint8_t rx_buffer[2];
 
@@ -342,7 +367,12 @@ uint16_t SCCB_Read_Addr16_Val16(uint8_t slv_addr, uint16_t reg)
 
 int SCCB_Write_Addr16_Val16(uint8_t slv_addr, uint16_t reg, uint16_t data)
 {
-    i2c_master_dev_handle_t dev_handle = *(get_handle_from_address(slv_addr));
+    i2c_master_dev_handle_t *dev_handle_ptr = get_handle_from_address(slv_addr);
+    if (dev_handle_ptr == NULL)
+    {
+        return -1;
+    }
+    i2c_master_dev_handle_t dev_handle = *dev_handle_ptr;
 
     uint8_t tx_buffer[4];
     tx_buffer[0] = reg >> 8;