I have a big problem to solve this system
$\Delta f-hf^2=0$
$|\nabla f|^2+hf^3=0$
where $h$ is a constant, $f$ is a 2-dimensional smooth function, $\Delta f$ is Laplacian of $f$ (i.e. $\Delta f=f_{xx}+f_{yy}$) and $\nabla f$ is the gradient of $f$.
ADD In first case $f$ is defined on $R^2$ and in second case $f$ is defined on surface $S$ ($f:S \rightarrow (0, \infty)$). is there a solution? Thank you for help
MODIFICATION after Igor Khavkine answer: and if the system is
$\Delta f-hf^2+cf=0$
$|\nabla f|^2+hf^3=0$
(c is another constant)